Skyrmion Echo in a system of interacting Skyrmions

TL;DR

This paper introduces the skyrmion echo phenomenon in interacting skyrmions confined in nanodisks, explaining its physical mechanism and potential for restoring skyrmion signals through magnetization switching.

Contribution

It proposes the concept of skyrmion echo, combining numerical and analytical methods, and explains how magnetization switching can restore skyrmion coherence.

Findings

Skyrmion echo can be generated in confined skyrmion systems.

Magnetization switching restores the initial skyrmion signal.

Dephasing is caused by lattice distortion, impurities, and skyrmion interactions.

Abstract

We consider helical rotation of skyrmions confined in the potentials formed by nano-disks. Based on numerical and analytical calculations we propose the skyrmion echo phenomenon. The physical mechanism of the skyrmion echo formation is also proposed. Due to the distortion of the lattice, impurities, or pinning effect, confined skyrmions experience slightly different local fields, which leads to dephasing of the initial signal. The interaction between skyrmions also can contribute to the dephasing process. However, switching the magnetization direction in the nanodiscs (e.g. by spin transfer torque) also switches the helical rotation of the skyrmions from clockwise to anticlockwise (or vice-versa), and this restores the initial signal (which is the essence of skyrmion echo).